Effects of Nitrogen in Sewage Treatment Plant Effluent on Organic Matter Target Indicator of TMDLs in Korea

This study examined the relationship between water quality indicators (five-day biochemical oxygen demand (BOD5) and ammonia nitrogen (NH3-N)) by modeling them at sewage treatment plants (STPs) receiving waters. Discharge loads from 2016 to 2018 were input into QUAL-MEV model, which is used for total maximum daily (TMDLs) in Korea, results showed that simulated BOD5 values decreased according reduction BOD discharged pollution load, while observed increased. was caused an increase load NH3-N effluence ratio STPs. Hence, model modified reflect real-world conditions. After inputting a calibration factor calculated based on real data measured of each type nitrogen, simulation repeated, achieving within ±20% values. confirmed lower part river varies change STP effluent. To better manage establish achievable targets, plan reflects linkage among indicators, such as TMDLs United States, should be introduced Korea.